I got 80% of the addressing done tonight!

I have a few questions:
1. A friend from HS is now engaged and I've only met him once very briefly (like 5 mins) do I address with 'and guest' or do I address with his name too?
2. A friend from college whom FI and I used to live with 3 years ago, but haven't seen much since, but I have kept in contact via email is now in a serious relationship and they just moved in together. FI and I have not yet met him. Do we address 'and guest' or put his name (i know his first name via my friend, but only know his last name because of facebook)?
TIA!